#include <stdio.h>

int main(int argc, char *argv[])
{

    int vul, d, t = 0;
    scanf("%d %d", &vul, &d);
    
    for (size_t i = 1; vul >= 0; i++)
    {
        vul = vul - d * 1;
        t += 2;
    }

    printf("%d", t);
    return 0;
}